I also do not have a built-in generator. I put a trailer hitch rack on the back and put the generator on that, along with extra fuel for it. But, as Skip426 said, lock it or lose it. A few weeks ago I was watching a yt thread and came across a post by a couple who had a generator stolen from the back of their rv while they were driving. They were in inch traffic - move an inch, stop, move an inch, stop - and the generator was only secured by a ratchet strap, not some sort of real locking mechanism, and when they stopped for fuel or something discovered that their generator was gone. My rack is secured to the rv with a locking clevis, and then the generator is secured to the rack with chain and a padlock.
1997 Pleasure-way Excel-RL
1997 DODGE RAM 3500 5.2L V8 318 MAGNUM
Charles, RVM174, Looking for the rainbow!!